Resumen
A condition in the request headers evaluated to false on the server.
Cuándo ocurre
Returned when If-Match / If-Unmodified-Since preconditions are not met.
Causas comunes
- Resource changed since the ETag was fetched
- Stale If-Match / If-Unmodified-Since value
Cómo solucionarlo
- Refetch the current ETag and retry
- Remove the failing precondition if not needed
Base en la especificación